Choosing jogging as your go-to cardio workout makes sense for a host of reasons: It's a formidable fat-burner, it tones your legs and butt, it makes your heart stronger by degrees and it even improves mood. Many women opt to jog on a treadmill rather than outside. One advantage of this is the ability to select your speed with precision. Given this convenience, just how fast should you go relative to your fitness level?
Defining "Best Benefit"
To determine what jogging speed best serves your purposes, have a clear goal. For example, are you training for a 5K road race or are you looking to lose weight? If your aim is to improve your times, do workouts in which you cover two to three miles at or below 5K race pace, broken into repetitions of 200 to 1,600 meters and separated by rest periods lasting half time time it takes you to run the reps. To train for a marathon, lots of mileage at a modest speed is the ticket. And to optimize weight loss, you need a mixture of intensity and distance, so your ideal speed will vary from day to day.
Lactate Threshold Running
If you're interested in doing sustained running at as high of a speed as you can maintain without going over the anaerobic edge into oxygen debt -- in which case you'll soon have to slow precipitously or stop -- then you need to figure out your lactate threshold pace. If you've recently run a 5K, then this speed is about 25 to 30 seconds per mile slower than that, according to "Running Times" magazine. If you don't know your 5K race pace, you can use your speed at 90 percent of maximum heart rate to estimate lactate threshold pace. A good estimate of your max heart rate is 220 minus your age.
Alternatives to Raw Speed
As is probably apparent by now, going flat-out on the treadmill is neither feasible nor desirable, save for select occasions. Therefore, you should design your training in a way that optimizes your speed under given conditions. For example, once a week, you can do a continuous uphill run by inclining the belt to 3, 4 or 5 percent and finding a speed you can maintain at these grades for at least 20 minutes. This pace will be far less than that you could maintain on the level, but as far as your heart and lungs are concerned, you may as well be running fast because you'll be very close to your lactate threshold.
The Need for Recovery
As much as running fast is worth your while -- after all, it builds racing fitness, burns extra fat by revving up your metabolism and can be exhilarating -- you can only do a fraction of your running at high intensity without physically breaking down or mentally burning out. That's why it's important for you to establish a "recovery pace" -- that is, a speed at which you accrue aerobic benefits but only minimally tax your system, allowing your body to recover from previous hard efforts and prepare for subsequent ones. This pace correlates to about 60 to 70 percent of your maximum heart rate. Bear in mind that this pace will become faster as your fitness improves.
Michael Crystal earned a Bachelor of Science in biology at Case Western Reserve University, where he was a varsity distance runner, and is a USA Track and Field-certified coach. Formerly the editor of his running club's newsletter, he has been published in "Trail Runner Magazine" and "Men's Health." He is pursuing a medical degree.